Laws of Motion JEE Advanced previous year questions with solutions

4 solved JEE Advanced questions on Laws of Motion, free to read — no sign-in needed. The full chapter has 15 questions; sign in to attempt the remaining 11 in the exam simulator.

1. Q1JEE Advanced Adv 2025 (Paper 1)
   A person sitting inside an elevator performs a weighing experiment with an object of mass 50 kg . Suppose that the variation of the height $y$ (in m ) of the elevator, from the ground, with time $t$ (in s ) is given by $y=8\left[1+\sin \left(\frac{2 \pi t}{T}\right)\right]$, where $T=40 \pi \mathrm{~s}$. Taking acceleration due to gravity, $g=10 \mathrm{~m} / \mathrm{s}^2$, the maximum variation of the object's weight (in N ) as observed in the experiment is _______ .
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   Answer: 2

   $y=8+8 \sin \frac{2 \pi t}{T}$ With respect to elevator, variation in weight will be $\begin{aligned} & \Delta \mathrm{W}=\mathrm{m}(\Delta \mathrm{a})_{\max } \\ & \Delta \mathrm{W}=\mathrm{m} \times 2 \omega^2 \mathrm{~A}\end{aligned}$ Here elevator is performing SHM $\begin{aligned} & \Delta \mathrm{W}=2 \mathrm{~m} \times\left(\frac{2 \pi}{\mathrm{~T}}\right)^2 \times \mathrm{A} \mathrm{N} \\ & \Delta \mathrm{W}=2 \times 50 \times\left(\frac{2 \pi}{40 \pi}\right)^2 \times 8 \mathrm{~N} \\ & \Delta \mathrm{~W}=2 \times 50 \times \frac{1}{400} \times 8 \mathrm{~N} \\ & \Delta \mathrm{~W}=\frac{800}{400} \mathrm{~N}=2 \mathrm{~N}\end{aligned}$
2. Q2JEE Advanced Adv 2008 (Paper 2)
   Statement 1 It is easier to pull a heavy object than to push it on a level ground. and Statement 2 The magnitude of frictional force depends on the nature of the two surfaces in contact.
   1. A.Statement 1 is true, Statement 2 is true, Statement 2 is a correct explanation for Statement 1.
   2. B.Statement 1 is true, Statement 2 is true, Statement 2 is not a correct explanation for Statement 1.
   3. C.Statement 1 is true, Statement 2 is false.
   4. D.Statement 1 is false, Statement 2 is true
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   Answer: (B)

   Both statements are correct. But statement-2, does not explain correctly, statement- 1 . Correct explanation is : "There is increase in nomal reaction when the object is pushed and there is decrease in normal reaction when the object is pulled (but strictly not horizontally).
3. Q3JEE Advanced Adv 2007 (Paper 2)
   Statement I A cloth covers a table. Some dishes are kept on it. The cloth can be pulled out without dislodging the dishes from the table. Statement II For every action there is an equal and opposite reaction.
   1. A.Statement I is true, Statement II is true; Statement II is a correct explanation for Statement.
   2. B.Statement I is true, Statement II is true; Statement II is NOT a correct explanation for Statement I
   3. C.Statement I is true, Statement II is false
   4. D.Statement I is false, Statement II is true
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   Answer: (B)

   The cloth can be pulled out without dislodging the dishes from the table due to law of inertia, which is Newton's first law. While the Statement II is true, but it is Newton's third law. $\therefore$ Correct option is (b).
4. Q4JEE Advanced Adv 2007 (Paper 2)
   A particle moves in the $X-Y$ plane under the influence of a force such that its linear momentum is $\mathbf{p}(t)=A[\hat{\mathbf{i}} \cos k t-\hat{\mathbf{j}} \sin k t]$, where $A$ and $k$ are constants. The angle between the force and the momentum is
   1. A.$0^{\circ}$
   2. B.$30^{\circ}$
   3. C.$45^{\circ}$
   4. D.$90^{\circ}$
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   Answer: (D)

   $$\begin{aligned} & \mathbf{F}=\frac{d \mathbf{p}}{d t}=-k A \sin k t \hat{\mathbf{i}}-k A \cos k t \hat{\mathbf{j}} \\ & \mathbf{p}=A \cos k t \hat{\mathbf{i}}-A \sin k \hat{\mathbf{j}} \end{aligned}$$ Since, F $\cdot \mathbf{p}=0$ $\therefore$ Angle between $\mathbf{F}$ and pshould be $90^{\circ}$. $\therefore$ Correct option is $(\mathrm{d})$.